Transition metal catalysts have been employed to prepare polymers and copolymers of .alpha.-olefins. For the most part, the polymer properties have been controlled or varied by changes in the process conditions as disclosed by Hogan et al in U.S. Pat. No. 2,825,721; by Walker et al in U.S. Pat. No. 3,351,623; "The Polymerization of Olefins by Ziegler Catalysts," Bergy, M. N., et al, Advances in Catalysis, Vol. 19, and "Supported Chromium Catalysts for Ethylene Polymerization," Annual Symposium, Joint Meeting of the American Chemical Society and Chemical Society of Japan, April 1-6, 1979.
It has now been discovered that the polymer properties can be varied by employing two different catalysts during polymerization of the .alpha.-olefin. Such polymerization process provides for one or more of the following:
(1) alteration of the physical properties of the polymer without changing process conditions; PA1 (2) change physical properties of the polymer without the use of hydrogen, PA1 (3) change polymer composition of copolymers by changing catalyst ratios rather than comonomer ratios and/or PA1 (4) increased catalyst efficiency.